[OSM-talk] The Return of the Highway tags and other junk

[Ben Robbins]

>Gate and cattle_grid go on their respective nodes, not ways or segements, 
>as
>I understand the spec, so that's not a problem is it?

They are phisical objects that have widths and lengths taht can varie.  
Therfore I would never tag them as a node, just as a building would be an 
area.

>And surely a footway and a track are mutually exclusive by the definitions
>in the spec. I wasn't party to the original thinking, but I presume the
>assumption is that in general there is a hierarchy so that one can walk
>along a track (or a cycleway or a primary) unless there are access tags on
>it, except for well-understood special cases such as motorway (or e.g.
>one-way assumed on a roundabout). Track means 'also a footway' by
>definition, yes?

Well thats one of the points I'm debating.  The track contiues well beyong 
the permissivie footway.  So if i just tag the track, and asume it has some 
access right (wich I would like someone to state), then I cannot use this 
where its private.  Alternatively it doesnt state access in wich case 
footway is the higher.  In either case this answer would mean that 1 part of 
the data gainned on the filed cannot be mapped.

>JOSM doesn't let you create them, but is there anything fundamental to stop
>one having multiple tag/value pairs with the same tag?

I don't know.  It would be helpful if it can though.

>when is an abandoned railway no longer a railway? If it is reused as a 
>track, has it then disappeared >as arailway, it's use subsumed? Taking this 
>further, is an abandoned raiway
>still such if it has housing built over it and is no longer a visible
>feature in the landscape?

I don't no of any 'official' way of defining it, but if the top of the rail 
is lined with rust its a good indication.  I would say an abandoned railway 
is allways an abandoned railway, just as the route of a roman road on OS 
maps is there when easy visual evedence isnt.  The independence of tags 
doesnt make this a problem as the houses and roads would render on top, but 
if a person was interested specifically in the route of the old railway, the 
informaion is there still.

>'Course of' railway (or Roman road, or filled in canal) may be useful 
>as....

Yes, I think the definition of abandoned on the standadised tags page, means 
that there is nolonger any rail there.  railway=disused would inply that 
visual elemenets remain.

>How should this be represented?  
>http://ktransit.com/transit/Germany/Wuppertal/Photos/wup-mr13.jpg

Well I don't know what its called, but it would fit under railway fine, just 
as any other type of railway would.

>Is the viaduct then a separate independent feature, which is for reasons of
>convenience attached to a Way, but if one were being pedantic should be
>separately represented? (What happens when a viaduct carries two adjacent
>Ways? The most common example is a dual carriageway - two separate ways in
>the spec - are carried across the same physical structure in some cases, 
>but
>often there are separate bridges for each carriageway. Do we care? Is it
>worth the bother? At the moment we can't represent the more common case
>where a they share the same structure because of the way the carriageways
>are represented).

I don't attach the viaduct tag to the way or those reasons.  Bridiges are 
too variable to have them on one tag.  E.G. this example contiues on and a 
couple of miles away joins another track.  The 2 rails bridge a road, and 
merge half way over. Therfore I have made 2 bridges that merge half way 
over.  I use the landuse none, and then draw the bridge borders.  But I 
think this is another debate of what is the correct way.

>If we make it too complicated, the cost of creating the thing puts people
>off. If we make it too simple there are odd cases like Wuppertal or shared
>bridges or new features following the course of an old railway, which are
>anomalies. In the end does it matter much?

I agree.  My tecnique for making bridges is more time consuming than just 
tagging a way.  On the other hand. ''In the end'' it does matter, because if 
many people dont wish to tag something acuratley, that shouldnt mean many 
others can't.

>If a change is proposed which can't be (mostly) automatically converted 
>from
>existing data, it needs a great deal more justification IMO than one which
>simply adds a new kind of feature. Manual changes at this stage are very
>hard to achieve, and it is probably better to live with a flaw in the
>original spec.

Tracktypes is additional, so can be.  Features and Borders as a means of 
grouping an array of scattererd tags into one key, rather than creating many 
new values.  It would involve a small amount of conversion, but by the 
responce/discussion on the proposed features page, I think these tags arnt 
used that much.

Ben

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